1. Field of the Invention
The present invention relates to navigational devices. More particularly, the invention relates to a combined GPS receiver and depth sounder unit that includes a single display screen that can be smoothly adjusted so that the area of the display screen devoted to a GPS map can be changed relative to the area devoted to a depth sounder display.
2. Description of the Prior Art
Many types of navigational devices exist for both recreational and professional use. For example, many fishermen, boaters, and other sportsmen use GPS receivers to determine and view their current location and depth sounders to determine the depth of a body of water.
Recently, GPS receivers and depth sounders have been combined in single units to permit users to determine both their current location and the depth of a body of water. These combined units typically include a single display screen that displays both a GPS map display and a depth sounder display.
Combined GPS receivers and depth sounder units allocate a fixed amount of their display screens for the GPS map display and the depth sounder display, for example, approximately 75% for the GPS map and approximately 25% for the depth sounder display. This fixed division of the display screen is a limitation because users may wish to adjust the relative size of the GPS map and depth sounder displays in certain circumstances. For example, a fisherman who is primarily interested in determining and viewing the depth of a body of water may wish to enlarge the depth sounder display relative to the GPS map display to provide more resolution for the depth display.
The present invention solves the above-described problems and provides a distinct advance in the art of navigational devices. More particularly, the present invention provides a navigational device with a single display screen that simultaneously displays two different sets of information and that permits an operator to selectively adjust the portion of the display screen that is devoted to each of the sets of information.
In one preferred embodiment, the navigational device is a combined GPS receiver and depth sounder unit that includes a first input port for receiving a sensor signal from a depth sounder transducer; a second input port for receiving a location signal; a display screen including a first display area for displaying information corresponding to the sensor signal and a second display area for displaying information corresponding to the location signal; and a computing device coupled with the display screen. The computing device is programmed to permit a viewer to selectively adjust the size of the first and second display areas relative to one another to change the relative portion of the display screen that is occupied by the first and second display areas. This display adjustment is smooth (i.e., finely adjustable) so that a viewer can select any number of different sizes for the first and second display areas within the limits of the overall size of the display screen and the resolution of the screen.
These and other important aspects of the present invention are described more fully in the detailed description below.